#!/bin/bash

# 定义主从服务器信息
MASTER_HOST="master_host"
SLAVE_HOST="slave_host"
USER="replication_user"
PASSWORD="password"

# 检查主服务器状态
check_master() {
    mysql -h $MASTER_HOST -u $USER -p$PASSWORD -e "SHOW STATUS LIKE 'Slave_IO_Running'" | grep -q "Yes"
    if [ $? -ne 0 ]; then
        echo "Master is down, initiating failover..."
        promote_slave
    fi
}

# 提升从服务器为主服务器
promote_slave() {
    mysql -h $SLAVE_HOST -u $USER -p$PASSWORD -e "STOP SLAVE;"
    mysql -h $SLAVE_HOST -u $USER -p$PASSWORD -e "RESET SLAVE ALL;"
    mysql -h $SLAVE_HOST -u $USER -p$PASSWORD -e "CHANGE MASTER TO MASTER_HOST='none', MASTER_AUTO_POSITION=1;"
    mysql -h $SLAVE_HOST -u $USER -p$PASSWORD -e "START SLAVE;"
    echo "Slave promoted to master successfully."
}

# 主循环
while true; do
    check_master
    sleep 5
done